Formerly, micro cellular systems may be broadly divided into two types. In one type of system, the transmission output from a wireless machine in a base station is reduced, thereby reducing the cell radius in the CMTS. This system has been implemented with the main purpose of increasing the repetition utilization efficiency of a frequency and thus increasing the number of mobile terminals to be accommodated per unit area. This system is essentially not different from a CMTS at all excepting that the cell radius is smaller, and the frequency band used in the MCS is the same as in the CMTS. In addition, in general, an operator of the CMTS controls and operates this system. An example of the system configuration of this system is shown in FIG. 3.
In FIG. 3, the base station 101 for the CMTS and the base station 102 for the MCS 102 are directly connected to the cellular switching station (mobile telephone switching office) 103, and the control and operation of each of the base stations 101 and 102 are all carried out by the cellular switching station 103 in a centralized manner. Therefore, countermeasures against fraudulent use of the base stations 101 and 102 are carried out through the cellular switching station 103 and are the responsibility of the operator of the cellular switching station 103.
The second type of system is one which provides a special mobile communication service by using a frequency band which is different from that for the CMTS, with a system configuration of miniaturized CMTS, and with a certain limited area as a service zone. For example, a system called wireless PBX is a typical example, and FIG. 4 shows an example of the system configuration. This system generally uses legally defined extremely low transmission power, thereby making it unnecessary for a specific operator to control and operate it, and a user purchases a whole system and controls and operates it as its own private facilities.
In FIG. 4 an in-house switching unit 201 is connected to a public telephone communication network. A control unit 202 is connected to the in-house switching unit 201. A plurality of base stations 203 are connected to the control unit 202 by wires. A mobile station 204 is connected to a base station 203 by wireless means, and 205 is a wireless zone constituted with a plurality of the base stations 203. Each of the constituting equipment and devices shown in FIG. 4 are generally small in size and light in weight, and can be easily moved and installed. Countermeasures against fraudulent use of these equipment and devices are taken by each user by its own independent method.
In recent years, there has appeared a new MCS which does not belong to any of the above-mentioned systems. While this system utilizes the same frequency band as the CMTS, it is an independent MCS like a wireless PBX which works by avoiding mutual interference with the CMTS, and therefore its system configuration is similar to that shown in FIG. 4.
Since an MCS of this type is installed in each user site, and the ownership of the system resides in each user, the daily control and operation is carried out by each user, but a cellular operator must be responsible for the control and operation of the frequencies.
However, since such a new MCS is small in size and light in weight, it can be relatively easily moved and installed. Therefore, a user can move and install an MCS from an initial location of installation to another location, depending on its own needs and convenience. Unless necessary procedures for the co-existence of an MCS and a CMTS are carried out properly at the location to which it has been moved, there is a possibility that an MCS may interfere and hinder a CMTS. Especially, in a case in which the location of the move is a territory of another cellular operator, it means that a wireless facility which the cellular operator at the location of move does not recognize is operated and it might develop into a serious problem of responsibility.